This application is based on applications Nos. H11-113047 and H11-114402 filed in Japan on Apr. 21, 1999 and Apr. 22, 1999 respectively, the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a display optical apparatus for projecting an image displayed on a reflection-type display panel.
2. Description of the Prior Art
One of conventional means of displaying an image is a projection-type display optical apparatus. Today, in display optical apparatuses of this type, a so-called reflection-type display panel such as a reflection-type liquid crystal display panel is employed. In addition, an illumination optical system is employed to illuminate efficiently and uniformly an optical image displayed on such a reflection-type display panel. Moreover, a microlens array or the like is disposed immediately in front of the reflection-type display panel to direct the illumination light emitted from the illumination optical system to the reflection-type display panel.
For example, a reflection-type display panel of a so-called single-panel type is used that has R, G, and B pixels arranged in a recurring pattern. Illumination light is separated into R, G, and B light beforehand, and the thus separated R, G, and B light is directed at different angles into individual microlenses of a microlens array, separately for each pixel group (here, a pixel group denotes a set of three different, i.e. R, G, and B, pixels) or for every predetermined number of pixel groups, so that the R, G, and B light is condensed individually onto the R, G, and B pixels of the reflection-type display panel.
However, in this construction, since the reflection-type display panel is illuminated with R, G, and B light that is shone thereon at different angles, the illumination light fans out greatly in the direction in which it is separated. In addition, since the pixels are illuminated through the microlenses, not only the illumination light fans out greatly in the direction in which it is separated, but also the light that has reflected from the reflection-type display panel, i.e. the projection light, then passes through the microlenses and thus fans out in another direction.
In a construction as described above, where a reflection-type display panel is illuminated with illumination light that fans out and the projection light reflected from the reflection-type display panel needs to be handled separately from the illumination light, it is necessary either to shine the illumination light on the reflection-type display panel at a large angle of incidence from an oblique direction and extract the light reflected regularly from the reflection-type display panel as projection light, or to use a polarization beam splitter that can handle light that fans out greatly.
However, illuminating a reflection-type display panel with illumination light shone thereon at a large angle of incidence tends to cause image distortion, and therefore it is difficult to project an image displayed on the reflection-type display panel onto a screen properly by directing the projection light obtained from such illumination light through a projection optical system. On the other hand, a polarization beam splitter that can handle light that fans out greatly cannot be realized with a conventional structure using a dielectric multilayer film. Normally, in a polarization beam splitter, as the angle of incidence varies, the transmittance for light of a given wavelength range incident thereon varies greatly. Therefore, with illumination light that fans out greatly and with the projection light obtained therefrom, particularly when a wide wavelength range is involved, it is difficult to handle the illumination and projection light separately.
An object of the present invention is to provide a display optical apparatus that can minimize the fanning out of illumination and projection light in the direction in which they are separated and that can be built with illumination and projection optical systems of simple construction.
Another object of the present invention is to provide a display optical apparatus that allows separate handling of illumination and projection light by the use of an ordinary polarization beam splitter even with illumination light that fans out greatly and with the projection light obtained therefrom, or even when a wide wavelength range is involved, and that can be built with illumination and projection optical systems of simple construction.
To achieve the above object, according to one aspect of the present invention, a display optical apparatus is provided with: an illumination optical system, including a color separation device, for separating light polarized in a predetermined polarization direction into light of different wavelength ranges traveling in different directions by use of the color separation device and emitting the thus separated light as illumination light; a reflection-type light modulation device for displaying an optical image; an illumination/projection separation optical system for directing the illumination light emitted from the illumination optical system to the reflection-type light modulation device and for emitting the light reflected from the reflection-type light modulation device as projection light; a microcylinderlens array, disposed between the color separation device and the reflection-type light modulation device, for focusing the illumination light on the reflection-type light modulation device in such a way that light of different wavelength ranges is focused separately; and a projection optical system for focusing the projection light emitted from a polarization beam splitter on an image plane. Here, the plane including the central ray of the illumination light and the central ray of the projection light is substantially perpendicular to the plane including the direction in which the color separation device performs color separation.
According to another aspect of the present invention, a display optical apparatus is provided with: an illumination optical system, including a color separation device, for separating light polarized in a predetermined polarization direction into light of different wavelength ranges traveling in different directions by use of the color separation device and emitting the thus separated light as illumination light; a reflection-type light modulation device for displaying an optical image; a polarization beam splitter having a polarization separation surface for directing the illumination light emitted from the illumination optical system to the reflection-type light modulation device and for emitting the light reflected from the reflection-type light modulation device as projection light, with the illumination light shone on the polarization separation surface in such a way that light of shorter wavelengths is shone thereon at larger angles of incidence; and a projection optical system for focusing the projection light emitted from the polarization beam splitter on an image plane.